Download Coronary arteries in tutorial revision: from normal variants to

Coronary arteries in tutorial revision: from normal variants
to significant anomalies
Poster No.:
467
Congress:
ESCR 2013
Type:
Poster Presentation
Authors:
C. Leal , H. M. R. Marques , R. Santos , M. S. C. Sousa , N.
1
2
2
2
2
2
3
4 1
Costa , P. Gonçalves , N. Cardim , A. Ferreira ; Lavradio/PT,
2
3
4
Lisboa/PT, Évora/PT, Lisbon/PT
Keywords:
Anatomy, Cardiac, Vascular, CT-Angiography, CT, Computer
Applications-Detection, diagnosis, Computer Applications-3D,
Contrast agent-intravenous, Congenital, Education and training
Any information contained in this pdf file is automatically generated from digital material
submitted to EPOS by third parties in the form of scientific presentations. References
to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in
any way constitute or imply ECR's endorsement, sponsorship or recommendation of the
third party, information, product or service. ECR is not responsible for the content of
these pages and does not make any representations regarding the content or accuracy
of material in this file.
As per copyright regulations, any unauthorised use of the material or parts thereof as
well as commercial reproduction or multiple distribution by any traditional or electronically
based reproduction/publication method ist strictly prohibited.
You agree to defend, indemnify, and hold ECR harmless from and against any and all
claims, damages, costs, and expenses, including attorneys' fees, arising from or related
to your use of these pages.
Please note: Links to movies, ppt slideshows and any other multimedia files are not
available in the pdf version of presentations.
www.escr.org
Page 1 of 45
Purpose
Normal coronary arteries include some anatomic variations of no clinical significance.
The same is true for some coronary anomalies, but other anomalies can be clinically
relevant and cause ischemia with risk of sudden death.
Our purpose is to illustrate in a didactic form the normal, the normal variation, the "benign"
anomalies and the "malignant" anomalies of the coronary arteries, emphasizing the
clinical importance of these findings.
Methods and Materials
Of the 3200 cardiac CT examinations performed in our Institutions (Hospital da Luz and
Hospital de Santa Marta, CHLC) during the last six years (2007-2013), we have selected
those with variants and anomalies of the coronary arteries.
In our series, we have found variants and anomalies such as:
- Multiple ostia;
- High take-off from the aorta;
- Ramus intermedius;
- Myocardial bridging;
- Duplication of left anterior descending artery;
- Single coronary artery with an arcade to supply the opposite vessels;
- Origin from the opposite or non-coronary sinus with an anomalous course interarterial,
retroaortic, prepulmonary or intraseptal;
- Origin from the pulmonary artery;
- Small intraventricular course of the right coronary artery;
- Coronary fistula to the right ventricle.
We will start by revisiting the normal coronary artery anatomy:
Page 2 of 45
Origin - Sinus of Valsalva
The aortic root has 3 aortic sinuses (that can be named sinus of Valsalva, sinus of
Morgagni or Petit sinus), including the left (left posterior), right (anterior), and noncoronary
sinus (right posterior), which collectively are known as the sinuses of Valsalva (figure 1).
- The left main coronary artery originates from the left sinus of Valsalva.
- The right coronary artery arises from the right coronary sinus of Valsalva (that has a
ventral/anterior position) at a slightly lower lever than the origin of the left main coronary
artery (figure 2).
- The noncoronary sinus of Valsalva has a dorsal/posterior position in the aortic valve.
Right coronary artery (RCA)
The right coronary artery (RCA) descends in the anterior right atrioventricular groove. It
is divided in proximal, middle and distal segments (figure 3).
Proximal RCA
- The conal branch arises from the proximal RCA in 50 to 60% of the individuals, to
suplly the right ventricle outflow tract.
It can serve as an important source of collateral supply to the left anterior descending
coronary artery (LAD), through the so-called "circle of Vieussens", in select cases of
severe left main coronary artery or proximal LAD disease.
- In 60% of people, the sinoatrial nodal branch arises from the proximal RCA and runs
along the right atrium wall, then through the interatrial septum to reach the sinoatrial node
near the superior vena cava entry (figure 4).
- Some smaller branches arise to the anterior free wall of the right ventricle.
Middle RCA
Page 3 of 45
- The halfway point between the RCA ostium and the acute margin of the right heart
border is the dividing point between the proximal and middle RCA segments and is
marked by the origin of a large acute marginal branch (figures 5 and 12).
Distal RCA
- Starts at the acute margin of the right heart border, halfway between the origin of the
acute marginal branch and the crux of the heart (the zone of junction of the interatrial
and interventricular septa).
- In 90% of the individuals, from the distal RCA arises a branch to the atrioventricular
node, that locates at the Koch's triangle, in the posteroinferior region of the interatrial
septum near the opening of the coronary sinus (a triangle enclosed by the septal leaflet
of the tricuspid valve, the coronary sinus and the membraneous part of the interatrial
septum) (figures 6 and 7).
In a right dominance, the most frequent (70%), the terminal portion of the distal RCA
gives off (figures 14 and 15):
- The posterior descending artery (PDA), that runs in the posterior surface of the
interventricular septum and supplies its posterior basal third;
- The posterolateral branch (PL), destined for the inferior free wall of the left ventricle.
Left main coronary artery (LM)
The left main coronary artery (LM) has 5 to 10 millimeters of extension and then
bifurcates, giving origin to the left anterior descending coronary artery (LAD) and left
circumflex coronary artery (LCX) (figures 8 and 13).
The left anterior descending coronary artery (LAD) courses in the anterior epicardial
ventricular septum directing to the apex.
It is divided in proximal, middle and distal segments (figures 8 and 9).
- Septal branches (S) arise from the LAD and supply the interventricular septum (the
two anterior thirds of the septum at the base and the totality of the septum at the middle
and apical regions).
Page 4 of 45
- Diagonal branches (D) originate from the LAD to reach the anterior free wall of the left
ventricle. The diagonals are varied in number and caliber and are labeled from proximal
to distal D1, D2, D3 and so forth.
Proximal LAD
- The first septal perforator (S1) or the first diagonal branch (D1) generally divides the
proximal and middle segments of the LAD.
Middle LAD
Distal LAD
- The middle segment runs from the first septal perforator origin halfway to the left
ventricular apex.
- The distal segment runs from this halfway point to the apex itself.
The left circumflex coronary artery (LCX) runs in the left atrioventricular sulcus.
Supplies the lateral wall of the left ventricle through the obtuse marginal branches (OM)
and sometimes variable portions of the inferior wall of the left ventricle.
It is divided in proximal and distal segments (figures 10 and 11).
Proximal LCX
- The proximal segment runs from the LCX origin to the origin of the first obtuse marginal
branch (OM1).
Distal LCX
- The obtuse marginal branches are varied in number and caliber and are labeled from
proximal to distal OM1, OM2, OM3 and so forth.
The artery to the sinoatrial node, in 40% of people, arises from the proximal LCX (figure
10).
Page 5 of 45
The branch to the atrioventricular node arises from the distal LCX in 10% of the
individuals.
In a codominance* or in a left dominance (less frequent - 20% and 10% respectively**)
the distal LCX gives (figures 16 to 19):
- Posterolateral left branch (only this one in a codominance);
- Posterior descending artery (both in a left dominance).
*Kim, S.Y.; RadioGraphics 2006; 26:317-334
**Young, P.M.; AJR 2011; 197:816-826
A codominance can also be the presence of a double posterior descending artery, one
from distal RCA and the other from the distal LCX.
Images for this section:
Fig. 1: The three aortic Valsalva sinus.
Page 6 of 45
Fig. 2: The ostiums of the coronary arteries.
Page 7 of 45
Fig. 3: RCA and its segments.
Page 8 of 45
Fig. 4: Branch to the sinoatrial node.
Fig. 5: Acute marginal branch of the RCA - division between proximal and middle
segments of the RCA.
Page 9 of 45
Fig. 6: Branches of the distal RCA.
Fig. 7: Branches of the distal RCA, with right dominance.
Page 10 of 45
Fig. 8: LAD and its segments. In this case, the distal LAD crosses the apex to reach the
inferior wall of the left ventricle.
Fig. 9: LAD and D1.
Page 11 of 45
Fig. 10: Sinoatrial node branch originating from the proximal LCX.
Fig. 11: LCX and OM branches.
Page 12 of 45
Fig. 12: Acute and obtuse margins of the heart, justifying the names of the branches left anterior oblique view of the heart.
Page 13 of 45
Fig. 13: 3D VRTs of the heart and coronary arteries.
Fig. 14: Dominant right coronary artery, originating PDA and PL.
Page 14 of 45
Fig. 15: Dominant right coronary artery, originating PDA and PL.
Page 15 of 45
Fig. 16: Codominance - PDA arises from RCA and PL arises from LCX.
Page 16 of 45
Fig. 17: Codominance - PDA arises from RCA and PL arises from LCX.
Fig. 18: Left dominance - the PDA and the PL branch arise from the LCX.
Page 17 of 45
Fig. 19: Left dominance - the PDA and the PL branch arise from the LCX.
Page 18 of 45
Results
Coronary artery variants and anomalies:
- Occur in less than 1% of the general population (0,3 to 1%*) and in 1 to 2%** of the
patients who underwent invasive conventional coronary angiography.
(* Kim, S.Y.; RadioGraphics 2006; 26:317-334)
(** Hague, C.; AJR 2004; 182:617-618)
- Are asymptomatic in the majority of cases.
- Can be associated to major congenital heart defects (like transposition of the great
arteries, single ventricle and Tetralogy of Fallot).
- Technical difficulties in performing invasive conventional coronary angiography,
percutaneous coronary interventional procedures or cardiac surgeries can happen.
- Of risk are the "malignant" coronary artery anomalies.
Variants versus anomalies - remains controversial
- Some anatomic variations and some coronary anomalies have no clinical significance.
- Anomalies with clinical importance are the ones with hemodinamic repercussion
and association with suden death, arrithmias,miocardial ischemia, coongestive cardiac
insuficiedncy and endocarditis (near 20% - Datta, J.;Radiology2005; 235:812-818).
- CT angiography is superior to conventional angiography in the detection and
characterization of coronary artery variants and anomalies.
Anatomic variations without clinical significance
Page 19 of 45
- Branches to the sinoatrial and atrioventricular node (as mentioned previously);
- Pattern of coronary artery dominance (as previously described)
"The most accurate definition of dominance would refer to the arterial supply to the
atrioventricular node. However, the node itself is not directly visualized on CT, and the
artery that supplies the atrioventricular nodal branches in the crux cordis typically supplies
the inferior wall through the PDA as well" - Young, P.M.AJR2011; 197:816-826.
- Early branching
Ramus intermedius is the middle branch of a trifurcation of the left main coronary artery,
that can behave as a diagonal branch or an obtuse marginal branch, to supply the anterior
or lateral free wall of the left ventricle respectively.
- Supernumerary ostiums
The conal branch can have a precocious origin from the ostium of the RCA or from a
separate ostium and can be multiple originating from different ostiums (figure 20 and 21).
The left main coronary artery can be absent and the LAD and LCX originate from
separate ostiums (figures 21 and 22).
- Minor variations of the ostiums positions at the Valsalva sinus
- Miocardial bridging without clinical significance
Miocardial bridging can be a variant and in the majority of cases is asymptomatic,
although in some cases can have hemodynamic significance. It occurs in 0.5% to 4.5%
of the patients who underwent invasive conventional coronary angiography.
The "myocardial bridge" is characterized by a typical intramyocardial route of a segment
of one of the major coronary arteries ("tunneled segment"), instead of the normal travel
in the epicardial fat. It is most common in the middle segment of the LAD artery.
Page 20 of 45
The "stepdown-stepup phenomenon" is defined as a localized change in direction of the
vessel course toward the ventricle. The "milking effect" is defined as diameter narrowing
limited to a restricted vessel segment with extraction of contrast agent not explainable
by normal coronary artery low. (Leschka, S.; Radiology: Volume 246: Number 3, March
2008)
We have to measure:
- Depth;
- Length;
- Grade of systolic compression (< or > 50%).
"Normally, only 15% of coronary blood flow occurs during systole" and "the presence of
tachycardia could unmask the ischaemic effect of a myocardial bridge" - Alegria, J.R.;
European Heart Journal (2005) 26, 1159-1168.
- S-shaped sinoatrial node artery
The S-shaped sinoatrial node artery is a relatively large vessel arising from the LCX
and coursing posteriorly between the left atrial appendage and the ostium of the left
superior pulmonary vein.
Differential diagnosis includes:
- Persistent left Superior Vena Cava;
- Recanalized Marshal lligament (left superior cardinal vein of the fetus);
- CABG surgery with saphenous vein grafts
- Right Superior Septal Perforator
The Right Superior Septal Perforator arises from the proximal RCA
or the right sinus of Valsalva and supplies the anterior septum.
- "Shepherd's crook" RCA
Page 21 of 45
"Shepherd's crook" RCA has a characteristic morphology resulting from a tortuous and
high course immediately after it originates from the aorta (figure 23).
It is important to measure the acuteness of the angle at the kink and the distance from
the RCA origin.
Coronary artery anomalies
In the article of So Yeon Kim, MD et al. (Coronary Artery Anomalies: Classification
and ECG-gated Multi-Detector Row CT Findings with Angiographic Correlation;
RadioGraphics 2006; 26:317-334), the classification presented is a modified version of
the classification system
developed by Greenberg et al (Greenberg, MA;RadiolClinNorthAm
1989;27:1127-1146) and comprehends anomalies of origin, anomalies of course and
anomalies of termination.
Here we also present the concept of anomalies of structure (http://
emedicine.medscape.com/article/153512-overview - "Isolated Coronary Artery
Anomalies"; Author Jamshid Shirani, MD, Chief Editor: Eric H Yang, MD; Updated Jan
4, 2012).
So, the classification of the coronary artery anomalies can be:
- Of number;
- Of origin;
- Of course;
- Of termination;
- Of structure.
However, coronary artery anomalies may also be classified as:
- Hemodynamically significant ("malignant");
- Hemodynamically insignificant ("benign").
Page 22 of 45
"Malignant" coronary artery anomalies:
- Interarterial course between the aorta and the pulmonary artery (occurs when the
LAD or LM arises from the right Valsalva sinus or when the RCA originates from the left
Valsalva sinus) (figures 30 to 32);
- ALCAPA (Anomalous origin of the Left Coronary Artery Arising from the Pulmonary
Artery) = Bland-Garland-White syndrome;
- Hemodynamically significant myocardial bridging (figure 28);
- Congenital coronary artery fistula (figure 44);
- Coronary artery atresia.
"Benign" coronary artery anomalies:
- All the other anomalies.
Number anomalies
- RCA duplication (with one or two ostiums)
- LAD duplication (figure 24)
Spindola-Franco et al. classified dual LAD in 1983:
Dual LAD consists of a short LAD that ends high in the anterior interventricular groove
and a long LAD that most commonly originates as an early branch of the LAD proper,
then enters the distal anterior
interventricular sulcus and courses to the apex (types 1-3);
Rarely originates anomalously from the right coronary artery (type 4).
(Agarwal, P.P. ;AJR2008; 191:1698-1701)
Page 23 of 45
Origin anomalies
- High origin
It usually occurs a few millimeters above the sinotubular junction, but distances of 2.0 cm
have been reported - Thakur R.; Int J Cardiol 1990; 26:369-371 (figure 25).
- Origin from the pulmonary artery trunk (figure 26 and 27), the right or left ventricle, one
of the bronchial arteries, internal mammary artery, the subclavian artery, internal carotid
or innominate artery
- ALCAPA = Bland-Garland-White syndrome
A coronary "steal" phenomenon occurs into the pulmonary artery and collateral circulation
develops between the RCA and left coronary artery.
Usually presents in infants or children and a progressive left-to-right shunting may
develop.
Origin and course anomalies
Origin
Solitary Ostium (single coronary artery)
Origin from the right Valsalva sinus:
- RCA continues as LCX and LAD
- RCA gives the LM
- RCA gives the LAD and LCX (figures 41 and 42)
Origin from the left Valsalva sinus:
- LM gives LAD, LCX and RCA
- LCX continues as RCA
Page 24 of 45
- LCX gives the RCA
- LAD gives the RCA
Various Ostiums
- Origin of LAD/LCX from the RCA (figures 36, 37, 39 and 40)
- Origin of LAD/LCX from the right Valsalva sinus (figures 30, 31, 33-35, 43)
- Origin of RCA from the left Valsalva sinus (figure 32)
- Origin from the non coronary Valsalva sinus (right posterior)
Course
The anomalously originated artery courses in one of four possible aberrant paths
(figure 29):
A - Anterior to the right ventricular outflow tract = Prepulmonic
B - Between a aorta e o tronco da artéria pulmonar = Interarterial
C - Through the supraventricular Crest in an intramyocardial septal route = Septal or
subpulmonic (figures 33 to 35, 39 and 40)
D - Dorsal to aorta = Retroaortic (figures 36 and 37)
An interarterial course is associated with risk of myocardial ischemia ("malignant
anomaly") because it generally occurs with:
- An hypoplastic ostium;
- An acute angular origin;
- Potential of compression between the great vessels during exercise, due to expansion
of the aortic root and pulmonary artery trunk root;
- And the artery with the anomalous course can be the dominant artery.
Page 25 of 45
- So, during or immediately after intense/extreme exercise, there is risk of sudden death
(till 30%).
-"In addition, some interarterial coronaries actually take an intramural course through the
wall of the aorta, which may cause them to be compressed during aortic pulsation" Young, P.M. AJR 2011; 197:816-826.
In a young patient with pectoris angina, myocardial infarction or cardiac syncope, a
coronary CT angiography must be done to rule out the possibility of having a congenital
coronary artery anomaly.
Termination anomalies
Fistula - Occur in 0.1% to 0.2% of the patients who underwent invasive conventional
coronary angiography. It is more common involving the right circulation.
Cardiac termination:
- Fistula to the right or left ventricle (figure 44);
- Fistula to the right or left atrium;
- Fistula to the coronary venous sinus or to the superior vena cava.
(Note: A coronary arcade is not like a fistula. It is a normal communication between two
coronary artery branches that regularly is of very small caliber and only becomes patent
when a connection between circulations is necessary.)
Extra-cardiac termination:
- Fistula to the pulmonary artery;
- Fistula to other artery like a bronchial artery (in this case, it has a systemic termination).
In both cases, according to the termination, left-to-right shunting can occur, with
consequences such as pulmonary hypertension. Coronary steal phenomenon is also a
problem.
Page 26 of 45
Structural anomalies (rarer)
- Congenital coronary stenosis;
- Coronary atresia;
- Coronary hipoplasia.
In most of the cases described in literature, the presentation is early in the 1st year of
life, although delayed presentation in adulthood has been reported.
A large conus collateral branch supplying the LAD may mimic a prepulmonic vessel and
is an example of a coronary arcade ("circle of Vieussens", mentioned above).
Images for this section:
Fig. 20: Conal branch with a separate ostium.
Page 27 of 45
Fig. 21: Multiple ostiums (conal branch, RCA, LAD and LCX).
Page 28 of 45
Fig. 22: Absence of the left main coronary artery - LAD and LCX with separate ostiums.
Page 29 of 45
Fig. 23: Shepherd's crook RCA.
Page 30 of 45
Fig. 24: LAD duplication.
Page 31 of 45
Fig. 25: High takeoff of the RCA.
Page 32 of 45
Fig. 26: The RCA originates from the pulmonary artery. The flow in the RCA is inverted
due to an arcade of connection that exists with the left main coronary artery.
Fig. 27: The RCA originates from the pulmonary artery. The flow in the RCA is inverted
due to an arcade of connection that exists with the left main coronary artery.
Fig. 28: LAD bridging, with reduction of the vessel caliber in cardiac systole.
Page 33 of 45
Fig. 29: The 4 possible anomalous paths of the vessel with ectopic origin.
Page 34 of 45
Fig. 30: "Malignant" anomaly - origin of the left main coronary artery from the right
Valsalva sinus, with an interarterial course.
Page 35 of 45
Fig. 31: "Malignant" anomaly - origin of the left main coronary artery from the right
Valsalva sinus, with an interarterial course.
Fig. 32: "Malignant" anomaly - origin of the right coronary artery from the left Valsalva
sinus, with an interarterial course.
Page 36 of 45
Fig. 33: LAD originating from the right Valsalva sinus, with a subpulmonic course.
Fig. 34: LAD originating from the right Valsalva sinus, with a subpulmonic course.
Page 37 of 45
Fig. 35: LAD originating from the right Valsalva sinus, with a subpulmonic course.
Fig. 36: Origin of the LCX from the proximal RCA, with a retroaortic course.
Page 38 of 45
Fig. 37: Origin of the LCX from the proximal RCA, with a retroaortic course.
Fig. 38: Small segment of the middle RCA with an intraventricular path.
Page 39 of 45
Fig. 39: Left coronary artery arising from the proximal RCA, with a subpulmonic path.
Fig. 40: The left coronary artery arises from the proximal RCA, with a subpulmonic path.
It gives the LAD and through an arcade the distal LCX is patent.
Page 40 of 45
Fig. 41: Single ostium with RCA giving a pre pulmonary arcade to supply the LAD and
LCX. Absense of the left main coronary artery.
Page 41 of 45
Fig. 42: Single ostium with RCA giving a pre pulmonary arcade to supply the LAD and
LCX. Absense of the left main coronary artery.
Page 42 of 45
Fig. 43: Origin of the left main coronary artery from the right Valsalva sinus.
Fig. 44: Fistula of the proximal RCA to the right ventricle.
Page 43 of 45
Conclusion
It is important for the Radiologist to know and understand the possible variations in the
origin, course, termination and structure of the coronary arteries, in order to determine
the relevance of these findings, the emphasis to be given in the examination report and
the influence in clinical management of these patients.
References
- Jonathan D. Dodd et al. Congenital Anomalies of Coronary Artery Origin in Adults: 64MDCT Appearance . AJR 2007; 188:W138-W146.
- So Yeon Kim, MD et al. Coronary Artery Anomalies: Classification and ECG-gated
Multi-Detector Row CT Findings with Angiographic Correlation. RadioGraphics 2006;
26:317-334.
- Jabi E. Shriki, MD et al. Identifying, Characterizing, and Classifying Congenital
Anomalies of the Coronary Arteries. RadioGraphics 2012; 32:453-468.
- Farhood Saremi et al. MDCT of the S-Shaped Sinoatrial Node Artery. AJR 2008;
190:1569-1575.
- Sunil Kini, Kostaki G. Bis, Leroy Weaver. Normal and Variant Coronary Arterial and
Venous Anatomy on High-Resolution CT Angiography. AJR 2007; 188:1665-1674.
- Phillip M. Young, Thomas C. Gerber, Eric E. Williamson, Paul R. Julsrud, Robert J.
Herfkens. Cardiac Imaging: Part 2, Normal, Variant, and Anomalous Configurations of
the Coronary Vasculature. AJR 2011; 197:816-826.
- Cameron Hague, Gordon Andrews, Bruce Forster. MDCT of a Malignant Anomalous
Right Coronary Artery. AJR 2004; 182:617-618.
- Jorge R. Alegria, Joerg Herrmann, David R. Holmes Jr, Amir Lerman, Charanjit S. Rihal.
Myocardial bridging. European Heart Journal (2005)26, 1159-1168.
Page 44 of 45
- Abdel-Rauf Zeina, Majed Odeh, Jorge Blinder, Uri Rosenschein, Elisha Barmeir.
Myocardial Bridge: Evaluation on MDCT. AJR 2007; 188:1069-1073.
- Sebastian Leschka,MD et al. Myocardial Bridging:Depiction Rate and Morphology
at CT Coronary Angiography-Comparison with Conventional Coronary Angiography.
Radiology, Volume 246, Number 3-March 2008: 754-762.
- Greenberg MA, Fish BG, Spindola-Franco H. Congenital anomalies of coronary artery:
classification and significance. Radiol Clin North Am 1989; 27:1127-1146.
- Jaydip Datta et al. Anomalous Coronary Arteries in Adults: Depiction at Multi-Detector
Row CT Angiography. Radiology 2005; 235:812-818.
Personal Information
- C. Leal is a Radiology Consultant at "Hospital de Santa Marta - CHLC".
- H. M. R. Marques, R. Santos, N. Costa are Radiology Consultants at "Hospital de Santa
Marta - CHLC" and at "Hospital da Luz".
- M. S. C. Sousa is a Resident of Radiology at "Hospital do Espírito Santo, Évora".
- N. Cardim is a Cardiologist Senior Consultant and P. Gonçalves and A. Ferreira are
Cardiologist Consultants at "Hospital da Luz".
Page 45 of 45